Juices are the extractable fluid contents of cells or tissues intended for direct consumption obtained by the mechanical process from sound, ripe fruits (Naz, 2018). They are non-alcoholic liquid products with diverse degree of clarity and viscosity (Sádecká et al., 2014). Fruit juices are rich in lycopene, ascorbic acid and citrulline that have been reported to have protection against cancer and cardiovascular disorders. The functionality of fruit juices have been attributed to their antioxidative properties (Okwori et al., 2017). Water melon is a common staple fruit in the world consumed as a dessert, fruit salad or used fo garnishing drinks (Mohammad, 2016). Cashew is a hard, drought-resistant, tropical tree, widely grown primarily for its nuts. Cashew apple, the pseudo-fruit, is fibrous, juicy and weighs approximately 8 times of the nut (Afolayan et al., 2016). Much (90% ) of the harvest is wasted after harvesting (Igbinadolor et al., 2017). Because, cashew apple has a characteristic astringent taste with biting sensation on the tongue and throat, blending it with other fruits may lessen its astringency (Rebouças et al., 2016). Raw pineapple juice is an excellent source of calcium, magnesium and manganese; however, pineapple mostly consumed around the world as canned products (Kaddumukasa et al., 2017). The demand for pineapple and its juice rises continually most especially due to its health benefits (Nwachukwu and Ezejiaku, 2014). It is usually used for blend composition to obtain new flavors in drinks. Most juice if not refrigerated has a very short shelf life (Okwori et al., 2017). Ginger is a spice with characteristic flavor due combination of zingerone, shogaols and gingerols and volatile oils. Fresh ginger is composed of 80.9% moisture, 23% protein, 0.9% fat, 1.2% minerals, 2.4% fibre and 12.3% carbohydrates (Olaniran and Abiose, 2018). Ginger has antibacterial effect and exhibits antifungal activity and extended the shelf life for 8 weeks in tomato paste. Ginger powder has been compared with synthetic antimicrobial agents such as potassium sorbate and citric acid in smoked fish (Oduah et al., 2015). Ginger is a commonly added to beverages for flavor. Garlic (Allium sativum) also regarded as Russian penicillin, stinky rose, tafanuwa in Hausa, ayo-ishi in Igbo and ayu in Yoruba (Neeraj et al., 2014; Olaniran et al., 2019a). Garlic comprises of sulphur containing compounds, the fresh bulb contains allicin, alliin and volatile oil. Garlic has exhibited antibacterial activity against Gram positive and Gram-negative bacteria (Olaniran et al., 2015). Fruit juice blends produced from different fruits combines basic nutrients present in these different fruits to provide a better quality juice nutritionally and organoleptically (Eke-Ejiofor, 2016). The inhibition of microbial growth and activity of microorganisms is one of the main purposes of the use of chemical preservatives such as benzoic, sorbic, lactic and acetic acid (Piper, 2018). Benzoic acid has been used in different forms as preservative in foods because of its established antimicrobial properties against yeasts and molds. They can denature protein, inhibit enzymes and alter or destroy the cell walls or cell membranes (Reut et al., 2004). Current reduction in consumption of chemically preserved foods is due to consumer’s awareness of the health implication of consumption of synthetic preservatives (Pongsavee, 2015). Replacing chemicals with natural preservatives (bio-preservatives) which have no side effects to the consumer is of interest. To provide alternatives with biological advantage over chemical preservatives without altering the organoleptic and physicochemical properties of fruit juice blends, the need to explore natural preservatives has been highlighted recently in scientific literature. In this regard therefore, the current study aimed to apply ginger-garlic mix; exploring their effectiveness as preservatives and assessing organoleptic acceptability of the new combination in fruit juice blends using cashew, pineapple and watermelon fruit for the storage study.

All samples were acceptable in terms of color, taste, flavor and texture. In terms of flavor and mouth feel, the order of preference of the juice were the preserved with 1% garlic-ginger > preserved with 1% ginger > preserved with 1% garlic > preserved with 1% ascorbic acid > and preserved with 1% sodium benzoate at ambient temperature of blends. Addition of preservatives enhanced the colour of the juice blends with the preserved with 1% ginger-garlic having the highest mean score of 8.88. There was no significant difference (p <0.05) in the sweetness of all the juice blends and the scores were in-between 8.77 to 8.94. Combination of ginger and garlic significantly (p <0.05) improved the mouth feel of the juice blends. In terms of overall impression, the most acceptable juice blend was the one preserved with 1% ginger-garlic (Table 1). In this the study all the juice blends that was garlic-ginger preserved was most acceptable and preferred. This observation may be due tempering of the pungent taste of garlic with pleasant scent of ginger resulting from mixing of equal volume of garlic and ginger filtrates. A similar observation has been reported by Mancini et al. (2019). The least preference for the garlic preserved juice blend, as observed in this study may be due to the strong pungent taste of garlic compared to that of those with ginger due to its pleasant (Mancini et al., 2019). In a study on the preservation of soymilk, Borode (2017) however reported low preference for garlic preserved soymilk.

In all the juice samples, pH was observed to show consistent decreases with period of storage. Maximum decrease in pH was observed in the juice sample that had no added preservative. At end of the five weeks storage period, pH decreases of 31.6, 25.1, 30.8, 30.9, 20.7 and 25.1% were observed in the juice samples without preservative, preserved with 1% ginger, 1% garlic, 1% garlic-ginger, 1% ascorbic acid and 1% sodium benzoate, respectively (Table 2).

For the titratable acidity, consistent increases were observed in the juice sample throughout the period of storage. Increases of 90.9, 133, 240, 35.7, 200 and 80% were observed in juice samples the juice samples without preservative, preserved with 1% ginger, 1% garlic, 1% garlic-ginger, 1% ascorbic acid and 1% sodium benzoate, respectively (Table 3). The consistent decrease in pH with period of storage as reported in this study is indicated to be vital to retaining the quality of tartness to the product. Decrease in pH with period of storage has been also been reported by previous investigators (Kaddumukasa et al., 2017; Olaniran et al., 2019b). It is opined that that low pH could enhance the stability of bioactive compounds during storage, thus extending shelf life (Chia et al., 2012).

In the case of specific gravity, increases were observed at the end of the five weeks period of storage. However, only minute increases of 8.4, 4.5 and 6.0 were observed were observed in juice samples preserved with, preserved with 1% ginger, 1 % garlic and 1 % garlic-ginger, respectively. Remarkable increase of 44.7% in specific gravity was observed in the unpreserved juice sample (Table 4). The total soluble solids in the preserved juice blends were observed to show consistent decreases with time. This observation was irrespective of the preservative used.

Highest increase (12.1%) in total solids was however observed in the unpreserved juice blend at the end of the five weeks storage period. At the end of storage, increases in total soluble solids of 6.3, 3.6, 5.5, 10.5 and 9.4% were observed for juice blends that were preserved with 1% ginger, 1% garlic, 1% garlic-ginger, 1% ascorbic acid and 1% sodium benzoate, respectively (Table 5). The stability documented in the study in the values of total soluble solids and specific gravity of preserved juice blends for weeks might be due to the presence of garlic, ginger, garlic-ginger filtrates, sodium benzoate and ascorbic acid added as preservatives. The preservatives slowed down the rate of fermentation of sugars present in the juices blends to water, carbon dioxide and ethyl alcohol at room temperature during storage (Kaddumukasa et al., 2017). In this study, the concentration of total soluble solid in the juice blends showed consistent increases with period of storage. Increase in soluble solids is an indicator of the rate of deterioration. The minimal increase soluble solid level observed in the preserved juice during storage could be due to decrease in the rate of conversion of organic acid to sugar thus increasing the shelf life of the juice. Similar observations have been reported by earlier researchers in related studies (Samad et al., 2019; Rapisarda et al., 2008). Generally, all the fruit blends (preserved and unpreserved), with the exception of the one preserve with 1% ginger-garlic showed growth of bacteria after one week of storage. Growth was only observed in the 1% ginger-garlic preserved juice from the third week of storage. At the end of the 5-week storage period, the bacterial count in the unpreserved juice was however remarkably higher than those of the preserved samples. The growth of lactic acid bacteria was observed in all the juice samples throughout the period of storage, except the 1% garlic and 1% ginger-garlic preserved samples where growth was observed only after 2 and 3 weeks of storage, respectively. For the total fungal counts, no growth was observed for the ginger-garlic preserved juice until after 5 weeks of storage. The 1% ginger and 1% garlic preserved juice showed growth after 2 weeks and 3 weeks of storage, respectively (Table 6). Combining the garlic-ginger as preservative in the study was the most effective during storage as microbial growth was greatly inhibited. This could be as result of a synergistic effect of ginger and garlic (Juan et al., 2017). It is opined that the major challenge in spoilage of fresh juice is the stability of the pH, natural microflora; chemical composition fruit juice (Ephrema et al., 2018). From the results from the study, addition of 1% garlic-ginger as preservative was effective in reduction of the microbial load and other physicochemical parameters. This may be due to the presence of essential oil from garlic and ginger, which are reported to have health promoting bioactive components offering consumers health benefits (Aneja et al., 2014; Baskaran et al., 2010). Thus, if 1% garlic-ginger is incorporated into industrial production of cashew apple, pineapple and water melon juice blends; it has better potential replacement for the chemical preservative during storage.

With respect to sensory accetability, the fruit blend preseved with the 1% garlic-ginger blend was the most accepatble (p <0.05). In presence of the biopreseravtives, the phyicochemical patrameters of the fruit blend showed stability during storage.

The study concluded that ginger and garlic could be used as effective biopreservatives in fruit juice blends at a minimum concentration at 1% and recommended as potential replacement for the chemical preservative during storage juice blends from cashew water melon and pineapple. The outcome of this study may expand the utilization of ginger and garlic more often in fruit juice production, create more job opportunities and reduce seasonal losses and wastage of fruits like cashew.

From the findings of this study, the biopreservatives (1% ginger, 1% garlic and 1% garlic-ginger extracts) compared favourably with the chemical preservatives (1% sodium benzoate and ascobic acid) used for preservation of the cashew water melon and pineapple juice blend. In addition, the study revealed 1% garlic-ginger extract as the most effective biopreservatives of all the biopresevatives used.